28 BULLETIN 137, U. S. DEPARTMENT OF AGRICULTURE. 



no vital significance, being mere manifestations of the epidermis. 

 The writer feels that the Svalof position has here been injured by a 

 defense that is too enthusiastic. The fact that variations may or 

 may not occur in a strain is" of little importance if the limits are de- 

 finable. No doubt there is variation, and it is especially noticeable in 

 the sparsely toothed varieties. A cactus under proper conditions 

 will display leaves, yet no one will question the propriety of describ- 

 ing the cacti as leafless plants. They never become foliage plants, 

 and no more do we expect a smooth-nerved Hanna selection to show 

 the strong toothing of the Manchuria. It may at times present a 

 few scattering teeth, but it would never become even moderately 

 strongly toothed, and certainly there are strongly toothed sorts that 

 are never anything else. 



VARIATIONS IN THE KERNEL. 



The kernel itself varies in many ways. The more definite varia- 

 tions not treated elsewhere are shape, dimensions, weight, and com- 

 position. 



SHAPE OF KERNEL. 



The shape of kernel is well established as a group distinction and 

 is often a varietal characteristic. The 6-rowed varieties are sharply 

 set off from the 2-rowed ones by the twisting of the lateral kernels. 

 Even the central kernel of the 6-rowed varieties, although it is not 

 twisted as are the lateral ones, is still of a shape different from that 

 of the 2-rowed sorts. In the 6-rowed varieties the greatest diameter 

 is nearer the distal end of the grain, while in the 2-rowed ones it is 

 nearer the proximal end. 



Within the groups the separations are naturally less marked. 

 Certain Finnish and Russian barleys may readily be distinguished 

 from the Manchuria because of their being less nearly oval in 

 shape. The extremities of the grain are more pointed, giving a 

 fusiform, or spindle-shaped, seed. The Goldthorpe barleys, espe- 

 cially such extreme types as Standwell, are readily separated from 

 the other 2-rowed forms. The Swedish Plant-Breeding Association 

 reports that Hannchen and Princess can be readily distinguished in 

 bulk samples by the shape of the kernel. Most of the distinctions, 

 however, are so dependent upon the relative proportions of the grain 

 that it is impossible to consider shape independent of dimensions. 



THE DIMENSIONS OF THE KERNEL. 



The barley kernel varies in length, width, and thickness. At times 

 one or all of these may constitute a varietal character. No other bar- 

 ley could be confused with the Smyrna. Its long grain is unique. 

 It is also very doubtful whether a second strain could be found that 

 possesses the unusual breadth of the Standwell. In all but these 



